Ma Chun-Min, Zhao Xin-Huai
Key Laboratory of Dairy Science, Ministry of Education, Northeast Agricultural University, Harbin 150030, China.
Foods. 2019 Aug 23;8(9):360. doi: 10.3390/foods8090360.
The non-covalent interactions between a commercial whey protein isolate (WPI) and two bioactive polyphenols galangin and genistein were studied at pH 6.8 via the multi-spectroscopic assays and molecular docking. When forming these WPI-polyphenol complexes, whey proteins had changed secondary structures while hydrophobic interaction was the major driving force. Detergent sodium dodecyl sulfate destroyed the hydrophobic interaction and thus decreased apparent binding constants of the WPI-polyphenol interactions. Urea led to hydrogen-bonds breakage and protein unfolding, and therefore increased apparent binding constants. Based on the measured apparent thermodynamic parameters like ΔH, ΔS, ΔG, and donor-acceptor distance, galangin with more planar stereochemical structure and random B-ring rotation showed higher affinity for WPI than genistein with location isomerism and twisted stereochemical structure. The molecular docking results disclosed that β-lactoglobulin of higher average hydrophobicity had better affinity for the two polyphenols than α-lactalbumin of lower average hydrophobicity while β-lactoglobulin possessed very similar binding sites to the two polyphenols. It is concluded that polyphenols might have different non-covalent interactions with food proteins, depending on the crucial polyphenol structures and protein hydrophobicity.
通过多光谱分析和分子对接，研究了市售乳清蛋白分离物（WPI）与两种生物活性多酚高良姜素和染料木黄酮在pH 6.8条件下的非共价相互作用。在形成这些WPI-多酚复合物时，乳清蛋白的二级结构发生了变化，而疏水相互作用是主要驱动力。洗涤剂十二烷基硫酸钠破坏了疏水相互作用，从而降低了WPI-多酚相互作用的表观结合常数。尿素导致氢键断裂和蛋白质解折叠，因此增加了表观结合常数。基于所测量的表观热力学参数，如ΔH、ΔS、ΔG和供体-受体距离，具有更平面立体化学结构和随机B环旋转的高良姜素对WPI的亲和力高于具有位置异构和扭曲立体化学结构的染料木黄酮。分子对接结果表明，平均疏水性较高的β-乳球蛋白对这两种多酚的亲和力优于平均疏水性较低的α-乳白蛋白，而β-乳球蛋白与这两种多酚具有非常相似的结合位点。得出的结论是，多酚与食物蛋白可能具有不同的非共价相互作用，这取决于关键的多酚结构和蛋白质疏水性。
